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Objective:To assess the feasibility of deformable image registration (DIR) in evaluating cumulative dose distribution of bladder and rectum of cervical cancer patients during helical tomotherapy (HT)-based intensity-modulated radiotherapy (IMRT) and high-dose-rate(HDR) brachytherapy.Methods:Clinical data of 18 patients were retrospectively analyzed. Cumulative bladder/rectum D 2cm 3 and high-risk clinical target volume (HR-CTV) D 90% parameters were calculated and compared to two direct parameter-adding methods with two registration-adding methods. Equivalent uniform dose (EUD group) and overlapping high dose (OHD group) methods were employed as parameter-adding methods. The registration-adding methods including rigid image registration (RIR group) and deformable image registration (DIR group) were adopted based on a commercial image registration software (MIM Maestro ?). The dice similarity coefficient (DSC) and mean distance to agreement (MDA) were measured to assess the accuracy of RIR and DIR. Results:In the EUD, OHD, RIR and DIR groups, the cumulative doses of bladder/rectum D 2cm 3 and HR-CTV D 90% were (80.11±3.59) Gy (EQD 2Gy), (82.23±3.46) Gy (EQD 2Gy), (80.99±6.01) Gy (EQD 2Gy) and (81.19±3.11) Gy (EQD 2Gy)( P=0.516); (72.90±3.58) Gy (EQD 2Gy), (73.83±4.28) Gy (EQD 2Gy), (72.45±6.05) Gy (EQD 2Gy) and (71.98±2.89) Gy (EQD 2Gy)( P=0.625), and (85.51±2.91) Gy (EQD 2Gy), (87.65±3.46) Gy (EQD 2Gy), (81.53±3.63) Gy (EQD 2Gy) and (85.81±3.30) Gy (EQD 2Gy)( P<0.001), respectively. The mean DSC of the bladder, rectum and HR-CTV were 0.69, 0.65 and 0.63 with RIR; and 0.85, 0.81 and 0.78 with DIR ( P<0.001), respectively. In DIR, the average MDA of bladder, rectum, and HR-CTV were 2.88, 2.48 and 2.66 mm, respectively. Conclusions:The cumulative DVH parameters among 4 groups show no significant difference in the bladder/rectum D 2cm 3/D 0.2cm 3. Since the DIR group achieves satisfactory volume matching of greater than 0.8 with DSC analysis, it can yield acceptable results for clinical application between HT IMRT and HDR BT for cervical cancer.
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Objective:To realize the interactive form evaluation of radiotherapy dose and the automatic calculation of conformity index (CI) and heterogeneity index (HI) in the Eclipse planning system.Methods:The Eclipse Scripting API application development interface and C# programming language were employed to develop it with script plug-ins combined with independent programs. The visual interface programming and call the relevant dose query function in the API were utilized to realize the interactive table dose evaluation and the automatic calculation of HI. The functions of calling dosage structure creation and structure Boolean operation in the API were adopted to realize the automatic calculation of CI.Results:15 clinical radiotherapy cases of nasopharyngeal carcinoma were selected. The dose evaluation results were statistically compared between this method and the module equipped in the Eclipse system. The results showed that the accuracy was consistent between these two methods ( P>0.05), whereas the evaluation efficiency of this method was significantly higher compared with that of the Eclipse system module ( P<0.05). Conclusions:The interactive evaluation form in this article has a friendly interface, which allows users to more conveniently perform dose assessment, multi-plan comparison, and calculation of CI and HI, which effectively improves work efficiency and can better serve the clinical and scientific research work of radiotherapy.
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Objective:To investigate the feasibilityof the adaptive radiotherapy using high-field MR-Linac systems for head neck cancers and perform the evaluation of target coverage and dose criteria.Methods:This study investigated 128 treatment plans of six patients who were treated on 1.5T MR-Linacsystems in Sun Yat-sen University Cancer Center in 2019, compared the differences in target coverage and dose criteria between the dose accumulation in the adaptive radiotherapy using MR-Linac systems and the reference plans, and evaluated the target coverage and dose criteria of each fraction of adaptive plan based on daily MRI anatomy.Results:There was no significant change in the target coverage and dose criteria for each treatment fraction(<1%). However, the change of lens dose was significant (maximum 98%). In addition, the result showed that there was no significant difference in target coverage and dose criteria between the dose accumulation in adaptive radiotherapy using MR-Linac systems and reference plans.In contrast, the average dose to lens was increased by 31.7%.Conclusions:It is feasible to perform adaptive radiotherapy using 1.5T MR-Linacsystems for head neck cancers according tothe evaluation of target coverage and dose criteria. Additionally, since the actual dose tolens was quite different from the reference plan, the lens exposure should be considered in clinical practice.
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Objective:To evaluate the impacts of tissue heterogeneity on dose calculation of cervical brachytherapy by comparing the doses calculated by two clinically used dose calculation method and the CT image-based Monte Carlo (MC) method.Methods:This study retrospectively selected 11 patients with cervical cancer treated with 3D brachytherapy in Anhui Provincial Cancer Hospital from January 2018 to June 2020. The dose distribution of each plan was calculated via three methods, dose calculation method described in American Association of Physicist in Medicine(AAPM) Task Group No. 43 Report (TG43-BT), Acuros BV(BV-BT) used to perform accurate dose calculations in high-dose-rate (HDR) brachytherapy with phantom heterogeneity, and CT image-based EGSnrc tool kit used to perform Monte Carlosimulation (MC-BT). The dose volumes( V3 Gy, V6 Gy, V9 Gy, and V12 Gy), target volume doses( D98, D90, D50), D2 cm 3 of organs at risk (OARs) calculated by the three methods were compared. Results:The HRCTV D90obtained by TG43-BT was 6.274 Gy, which was even overestimated by around 5% compared to the result calculated by MC-BT. Meanwhile, TG43-BT overestimated the dose volumesand the target volume doses compared to MC-BT.Except for D50 and V12 Gy, the differences between the doses to tumor calculated by BV-BT and MC-BT were not statistically significant( P>0.05). There was also no significant statistical difference between the D2 cm 3 of rectum, small intestine, and sigmoid calculated by BV-BT and MC-BT ( P>0.05). In contrast, the dose to D2 cm 3 of bladder determined by MC-BT was 4.609 Gy, which was notably higher than those deter mined by TG43-BT and BV-BT. Conclusions:TG43-BT overestimated the doses to tumor targets and most OARs since the effects of tissue heterogeneity were not taken into consideration. BV-BT performed efficient calculation and most of the dose distributionin target volume and OARs obtained by BV-BT were consistent with that calculated by MC-BT. Nevertheless, low accuracy occurred for the regions near the sources and full bladder, which warrants further caution in clinical evaluation.
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Objective To evaluate annual skin equivalent dose and annual effective dose to consumers arising from three types of cloths samples containing naturally occurring radioactive material (NORM).Methods Firstly,measurement of radioactivity in three types of cloths were made with γ-ray spectrometer.And then,theoretical exposure scenarios were simulated with Monte Carlo software to calculate organ dose and effective dose by using ICRP reference voxel male phantom.Finally,annual skin equivalent dose and effective dose to consumers from these cloths samples were evaluated.Results In the wrapped and covered estimation models used in this study,sample mass ranged from 135 to 7 197 g,annual skin equivalent dose to consumers from these cloths samples from 155.41 to 9 028.61 μ Sv,and annual effective dose from 11.91 to 1 234.44 μSv.Conclusions NORM-added consumer products would cause some radiation hazard to human body.
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Objective@#To evaluate annual skin equivalent dose and annual effective dose to consumers arising from three types of cloths samples containing naturally occurring radioactive material (NORM).@*Methods@#Firstly, measurement of radioactivity in three types of cloths were made with γ-ray spectrometer. And then, theoretical exposure scenarios were simulated with Monte Carlo software to calculate organ dose and effective dose by using ICRP reference voxel male phantom. Finally, annual skin equivalent dose and effective dose to consumers from these cloths samples were evaluated.@*Results@#In the wrapped and covered estimation models used in this study, sample mass ranged from 135 to 7 197 g, annual skin equivalent dose to consumers from these cloths samples from 155.41 to 9 028.61 μSv, and annual effective dose from 11.91 to 1 234.44 μSv.@*Conclusions@#NORM-added consumer products would cause some radiation hazard to human body.
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Objective: This study aims to investigate the efficacy and safety of the CT-guided three-dimensional brachytherapy combined with three-dimensional conformal radiotherapy in patients with locally middle- and late-stage cervical cancer. Methods: Ninety-seven patients with stage II A-IV locally middle- and late- stage cervical squamous-cell carcinoma were treated with CT-guided three-dimensional brachytherapy combined with three-dimensional conformal radiotherapy. The short-term response was observed. The survival analysis was conducted by Kaplan-Meier method, and the univariate analysis of prognosis was performed by using log-rank test. The high-risk clinical target volume (HR-CTV) D90, D2cc of bladder, rectum and sigmoid colon and equivalent dose in 2 Gy per fraction (EQD2) were calculated. Results: The overall 2-year survival rate and 2-year progression-free survival rate of 97 patients were 93.8% and 92.1%, respectively. The differentiation degree and tumor size were significantly correlated with the overall survival (both P < 0.05). According to Radiation Therapy Oncology Group (RTOG) acute and late radiation reaction evaluation criterion, rates of grades 1 and 2 acute lower digestive adverse reaction were 15.5% (15/97) and 12.4% (12/97), respectively. The acute gastrointestinal adverse reaction grading was associated with HR-CTV D90 EQD2 (P = 0.027). The rate of grades 3 and 4 late digestive system adverse reactions was 1.0% (1/97). Conclusion: CT-guided three-dimensional brachytherapy combined with three-dimensional conformal radiotherapy in the treatment of locally middle- and late-stage cervical cancer has good efficacy, and the rate of late severe adverse reaction is low.
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Objective To study the impact of heartbeat on the left ventricular myocardial (mLV) and the left anterior descending (LAD) coronary arterial dosimetry following intensity modulated radiotherapy (IMRT) for left-sided breast carcinoma.Methods A total of 15 female patients who received electrocardiography gated 4D-CT scan in inspiratory breathing-holding were enrolled.According to cardiac cycle,20 time-phase images were reconstructed from 0 to 95％ at 5％ interval.Then,the mLV and the LAD were delineated respectively and the IMRT plans of the left breast carcinoma were generated based on 0％ phase CT images.The volume and dice similarity coefficient (DSC) of the mLV were calculated,and the variation range of the mLV and the LAD dose-volume indexes were compared among different phases.Results The average rate of DSC variation of mLV was eightfold of volume,which reached to 472.07％,and the average change rate of mLV (Dmean) was up to 41.95％.The difference of the mLV's volume and DSC was statistically significant between the maximum and minimum(t =-6.585,-28.870,P＜0.05),as well as the D V10,V20,V30 and V40(t=-5.260,-4.084,-3.592,-3.273,-2.566,P ＜0.05).The average change rate of the LAD's D was up to 130.14％.The difference of D V10,V20,V30 and V40 of LAD was statistically significant between the maximum and minimum(t =-9.758,-8.810,-8.682,-7.853,-6.205,P ＜ 0.05).Conclusions The dosimetry impact of heartbeat on mLV and LAD should not be ignored.
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Objective To study the target setup margin and dose evaluation for cervical cancer patients with volume-modulated arc therapy in the off-line adaptive radiation therapy (off-line ART),Methods A total of fifty patients with cervical cancer were randomly divided into test group and control group.Cone beam CT scanning was performed twice a week,the setup errors in directions of LR,AP and CC were recorded in the whole treatment process.The target setup formula was used to calculate the new CTV-PTV setup margin.At the same time,the setup error was returned to planning isocenter (ISO).For the control group,the dose was recalculated on the basis of the original PTV after considering ISO shift.For the test group,the dose was also recalculated after the new extended boundary of the target.The dosimetric parameters of CTV and organs at risk (OAR) were evaluated between two groups after dose recalculation.Results According to the target setup formula,extended boundaries of CTV in the direction of LR,AP,CC were 0.45,0.46 and 0.82 cm,respectively.The test group increased in CTV with D100％ and D95％ (t =-8.16,-6.73,P ＜0.05) and decreased in femoral head with V40,V30 and D (t=3.14,-9.52,-7.48,P＜0.05) than the control group.The test group decreased in the pelvis with V34 and D than control group (t =10.14,-9.38,P ＜0.05).Conclusions The CTV-PTV setup margin and the dose of OAR were effectively reduced,and the coverage of target area was extended when the off-line ART technology was conducted in the volume-modulated arc therapy for cervical cancer.
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Objective To describe a simplified generic procedure to evaluate the external exposure dose evaluation in radiological emergency, and to compile the corresponding computer software. Methods Based on the related reports of IAEA, this generic procedure of external exposure dose evaluation in radiological emergency was compiled to computer software by Visual Basic 6.0. Results The generic procedure for evaluation of external exposure dose could be used in the external exposure radiation accident emergency. The actual accident data were input in this software, then the results from this software agreed with those of the actual accident well. The maximum error was 40% , and the minimum error was 6%.Conclusions The generic procedure for evaluation of external exposure dose could provide practical emergency response guidance. The software might help to evaluate the accidental dose more quickly and accurately, and provide scientific basis to take the immediate response actions.
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The stereotactic radiosurgery (SRS) describes a method of delivering a high dose of radiation to a small target volume in the brain, generally in a single fraction, while the dose delivered to the surrounding normal tissue should be minimized. To perform automatic plan of the SRS, a new method of multi-isocenter/shot linear accelerator (linac) and gamma knife (GK) radiosurgery treatment plan was developed, based on a physical lattice structure in target. The optimal radiosurgical plan had been constructed by many beam parameters in a linear accelerator or gamma knife-based radiation therapy. In this work, an isocenter/shot was modeled as a sphere, which is equal to the circular collimator/helmet hole size because the dimension of the 50% isodose level in the dose profile is similar to its size. In a computer-aided system, it accomplished first an automatic arrangement of multi-isocenter/shot considering two parameters such as positions and collimator/helmet sizes for each isocenter/shot. Simultaneously, an irregularly shaped target was approximated by cubic structures through computation of voxel units. The treatment planning method by the technique was evaluated as a dose distribution by dose volume histograms, dose conformity, and dose homogeneity to targets. For irregularly shaped targets, the new method performed optimal multi-isocenter packing, and it only took a few seconds in a computer-aided system. The targets were included in a more than 50% isodose curve. The dose conformity was ordinarily acceptable levels and the dose homogeneity was always less than 2.0, satisfying for various targets referred to Radiation Therapy Oncology Group (RTOG) SRS criteria. In conclusion, this approach by physical lattice structure could be a useful radiosurgical plan without restrictions in the various tumor shapes and the different modality techniques such as linac and GK for SRS.